Cathode structure for electrolytic apparatus



July 29, 1969 Q TOLLE ET AL 3,458,425

CATHODE STRUCTURE FOR ELECTROLYTIC APPARATUS Filed Jan. 9, 1967 ATTORNEYS United States Patent 01 fice 3,458,425 Patented July 29, 1969 3,458,425 CATHODE STRUCTURE FOR ELECTROLYTIC APPARATUS Charles I. Tolle, 4308 Poplar St. 70808, and Raymond M. Estes, Rte. 5, Box 642 70821, both of Baton Rouge, La.

Filed Jan. 9, 1967, Ser. No. 607,952 Int. Cl. C22d 1/02; B01k 3/02 US. Cl. 204-280 8 Claims ABSTRACT OF THE DISCLOSURE The disclosure describes appararatus for electrolytically extracting metals from salts in solution including a novel cathode structure which greatly facilitates the removal of deposited metal. More specifically, the novel cathode structure comprises a shaft having a plurality of flexible, preferably eversible circular concave members mounted in spaced relation thereon. The concave members are Sufficiently flexible that they may be easily everted so as to cause the metal deposited thereon to pop off.

Background of the invention This invention relates to electrolytic apparatus in general, and, more particularly, to electrolytic apparatus for extracting metal from metal salts in solution by causing the electrolytic deposition of free metal upon the cathode structure.

One application of such electroytic apparatus has been the removal of silver from photographic solutions such as hypo solutions. In such apparatus it is common toprovide a rotatable cathode structure so that the surface of the cathode structure can be maintained in constant motion with respect to the hypo solution, thereby providing for the uniform deposition of the silver on the surface of the cathode structure and to prevent the accumulation of reaction products in the hydro solution in the vicinity of the cathode.

One type of prior art cathode structure comprises a rotatable shaft extending into the solution and a plurality of fiat disc mounted on said shaft in parallel spaced relation along the length thereof. The entire assembly is electrically conductive and acts as the cathode for the electrolytic process, silver being deposited on all surfaces thereof. In order to remove the deposited silver from this prior art cathode structure, it has been necessary to remove the discs from the shaft and bend them in order to cause the deposited silver to break away. It was also necessary to chip or abrade the silver deposited on the shaft itself. The discs then had to be replaced on the shaft in order to restore the apparatus to readiness for further processing of the solution. Hence, it is apparent that the removal of the deposited silver from the prior art cathode structures was both a tedious and a time consuming operation which impairs the overall efficiency of the apparatus by interrupting its operation for substantial periods of time.

Summary of the invention It is therefore an object of this invention to provide apparatus for electrolytically extracting metals from salts in solution including a novel cathode structure which greatly facilitates the removal of the deposited metal.

In accordance with the above object, the present invention provides apparatus for electrolytically extracting metals from metal salts in solution including a cathode structure comprising an electrically conductive shaft extending into the solution to be processed, a plurality of non-conductive annular spacers adapted to fit over said shaft and protect it from contact with the solution, and

to pop off, preferably by eversion. The non-conductive I spacfers prevent metal from being deposited on the shaft itsel An advantage of this invention is that the deposited metal may be easily removed without disassembling the cathode structure. More particularly, the deposited metal can be removed simply by firmly stroking ones hand or an appropriate tool across the peripheral edges of the conductive members in a direction parallel to the axis of the shaft. This action causes the concave members to be evereted thus causing the deposited metal to pop off.

A further advantage of this invention is that, as a result of the ease and speed with which the deposited metal may be removed from the cathode structure, the overall efiiciency of the apparatus is enhanced by permitting the processing of the solution to be resumed after only a momentary interruption for the purpose of removing the deposited silver.

These and other objects and advantages of the present invention will be more clearly understood from the following description and accompanying drawings which set forth the principle of the invention and, by way of example, the presently preferred mode of applying that principle.

Brief description of the drawings FIG. 1 is an elevation view, partly in cross-section, of apparatus for extracting metals from salts in solution including the novel cathode structure of the present invention.

FIG. 2 is a plan view of one of the concave conductive members of the cathode structure.

FIG. 3 is a detailed cross-section taken along the line 3-3 of FIG. 1 of a portion of the cathode structure showing the concave conductive members in their normal condition.

FIG. 4 is an elevation view of a portion of the cathode structure showing the concave conductive members in their everted condition.

Description of the preferred embodiment Referring now to FIG. 1 for a more detailed description of the preferred embodiment of the present invention, there is shown apparatus suitable for electrolytically extracting metals from salts in solution. In general the apparatus includes a motor 1 which is connected to a speed reduction worm gear 2. Motor 1 is supported by base plate 3 which is constructed to fit over the top of tank 4 which contains the solution to be processed such as, for example, a hypo solution. Base plate 3 may be made of any suitable material which will not be attacked by the solution to 'be processed and which will insulate the cathode and anode elements of the apparatus from each other. For example, base plate 3 may be made of polymerized methyl methacrylate, such as Lucite, which possesses an additional advantage in that it permits a viewing of the elements in operation.

Output shaft 6 of speed reduction gear 2 projects downward through a suitable opening in base plate 3'. R0- tatable cathode structure 7 is connected to output shaft 6 by means of a suitable coupling 8, thereby permitting a shearing between elements of said structure and the solution.

A pair of anodes 11 and 12 project downward into the solution from base plate 3. The anodes 11 and 12 include carbon rods 13 and 14 which are press fitted into plastic rod holders 15 and 16 which are in turn mounted on'base plate 3. Carbon rods 13 and 14 may be ordinary welding rods tapped-at their upper ends to receive suitable threaded electrical conductors, which in turn may be connected to a power source.

The apparatus includes suitable means for applying a D.C. voltage betweenthe cathode structure 7 and the anodes 11 and 12 so as to carry out the electrolytic process. FIG. 1 shows rectifier box 18 mounted on base plate 3 for converting generally available A.C. electrical power to the D.C. power required for the purpose of the electrolytic process. The positive voltage output from rectifier 18-is applied to the carbon rods 13 and 14 of anode elements 11 and 12 by means of suitable conductors not shown. The negative output voltage from rectifier 18 is applied to the rotatable cathode stucture 7 by means of a similar conductor not shown. It is to be understood, however, that although rectifier 18 is shown in the preferred embodiment of the apparatus, other means for supplying a D.C. voltage between the anodes 11 and 12 and'the cathode structure 7 may be employed within the scope and spirit of the present invention. For example, a D.C. voltage might be supplied by means of a battery.

Referring in greater detail to cathode structure 7 shown in FIG. 1, shaft 20 may be made of any suitable material which is both electrically conductive and also preferably resistant to corrosive effects of the solution to be processed. For example, in the preferred embodiment of the present invention, shaft 20 is made of stainless steel. Collar 21 is fixedly mounted on shaft 20 so as to hold concave members 22 in position. Collar 21 may be made of any material which will not be attached by the solution to be processed. In addition, it may be deemed desirable that collar 21 be made of a non-conductive material so as to prevent the deposition of metal thereon. For example, collar 21 may be made of Lucite.

As shown in FIG. 2, concave members 22 are provided with suitable holes or openings at their centers so as to permit them to be slid onto shaft 20. Concave members 22 are made of a suitable electrically conductive and cor rosion resistant material such as, for example, stainless steel. Further, concave members 22 are in electrical contact with shaft 20 and are maintained in spaced relation by means of spacers 23 which may suitably be made of a suitable corrosion resistant material, and the exterior surfaces of which may be non-conductive so as to prevent a deposition of metal thereon. For example, spacers 23 may be made of sections of plastic pipe pressed over stainless steel.

Concave members 22 and spacers 23 are secured on shaft 20 by means of nut 24 which threadedly engages shaft 20 at the lower extremity thereof. The tightening of nut 24 forces concave members 22 and spacers 23 against collar 21, and the resulting tight fit between the elements serves to provide a seal which protects shaft 20 from the solution to be processed and thereby prevents metal from being deposited thereon.

Referring to FIGS. 3 and 4 for a better understanding of the manner in which the deposited metal is removed from cathode structure 7, it is noted that in the preferred embodiment of the present invention members 22 are normally concave upward as is shown in FIG. 3. After metal indicated by dots on the drawing has been caused to be deposited on members 22 by means of the electrolytic process, cathode structure 7 may, if desired, be removed from the solution and the members 22 are everted so as to cause the deposited metal to pop off. FIG. 4 shows concave members 22 in their everted condition after removal of the deposited metal.

The eversion may be accomplished by firmly stroking concave members 22 across their peripheries in a downward direction parallel to the axis of shaft 20 using one hand or both hands simultaneously, or with the aid of a tool that will not damage the members. The resulting distortion of both the upper and undersurfaces of each concave member 22 is so rapid and drastic and has such a snapping action that the deposited metal is caused to pop off leaving concave members 22 completely clean and ready for reirnmersion in the solution to be processed. No deposited metal is required to be removed from shaft 20 when nonconductive spacers 23 are used to prevent the deposition of metal thereon. The removal of the deposited metals as described requires but a few minutes interruption in the processing of the solution.

In the preferred embodiment of this invention, the concave members 22 are circular in shape with a diameter of approximately 5 inches, a thickness of approximately 0.019 inch, and a concavity which amounts to a depth of 7 approximately A; to A of an inch at the center of the member. This thickness of stainless steel together with the concavity of the member simultaneously provides sufficient rigidity for operational purposes and sufficient flexibility to permit effective eversion. It will be understood, however, that the shape, size, concavity, number, arrangement, separation, location and thickness of the members 22 may be varied within the scope and spirit of the invention, as may also be the case with the anodes.

It will be appreciated by those skilled in the art that although, in the preferred embodiment of this invention,

members 22 are connected to the D.C. power source through electrically conductive shaft 20, other means for supplying D.C. power to members 22 may be employed. Further, although the invention has been illustrated by reference to apparatus including a rotatable cathode structure 7, it will be understood that the principles of the invention are equally applicable to static electrode structures. It will also be apparent that other modifications and adaptations of the apparatus may be made without departing from the spirit and scope of the invention as set forth with particularity in the appended claims.

What is claimed is:

1. Apparatus for electrolytically extracting metal from salts in solution, a cathode member comprising:

a shaft extending into the solution,

a plurality of spacers mounted on said shaft, and

a plurality of electrically conductive-flexible concave members mounted on said shaft and maintained in spaced relation along the length thereof by said spacers, said concave members being capable of being everted so as to cause metal deposited thereon to pop off.

2. Apparatus for electrolytically extracting metal from salts in solution, as described in claim 1, wherein said shaft is made of an electrically conductive corrosion resistant material.

3. Apparatus for electrolytically extracting metal from salts in solution as described in claim 2, wherein the external surface of said spacers are made of an electrically non-conductive material so as to prevent the deposition of metal on said shaft.

4. Apparatus for electrolytically extracting metal from salts in solution, as described in claim 3, wherein said flexible concave members are mounted so that the principal planes of said members are perpendicular to said shaft.

5. Apparatus for electrolytically extracting metal from salts in solution, as described in claim 4, wherein said flexible concave members are circular in shape.

6. Apparatus for extracting metal from salts in solution, as described in claim 5, wherein said flexible concave members are made of a corrosion resistant material.

7. Apparatus for extracting metal from salts in solution, as described in claim 6, wherein the corrosion resistant metal is stainless steel.

8. Apparatus for electrolytically extracting metal from salts in solution comprising:

an electrically conductive shaft extending vertically into the solution, said shaft being unsupported at its lower end,

a plurality of non-conductive annular spacers mounted on said shaft,

a plurality of electrically conductive concave circular eversible cathode members concentrically mounted along said shaft and maintained in spaced relation along the length thereof by said spacers,

at least one elongated anode member extending vertically into the solution adjacent the peripheral edges of said cathode members,

means for applying a DC voltage between said cathode member and said anode members, and

means for rotating said shaft so as to cause a shearaction between said concave circular cathode members and the solution.

References Cited UNITED STATES PATENTS 5/1957 Duesenberg et al. 204-289 1/1959 Dufour et al. 204-83 US. Cl. X.R. 

